Field
The described technology generally relates to a method for transmitting information between a plurality of radioelectric stations, each station comprising a transmitter and a receiver, the information comprising NbMot words of data, NbMot being an integer strictly greater than 1. The described technology also relates to a transmission network comprising a plurality of radioelectric stations.
Description of the Related Technology
The described technology in particular relates to the case where the information to be transmitted has a size larger than the size of a radio packet dedicated to transporting that information. The described technology also relates to the case where it is necessary to repeat the sending of the information several times in order to guarantee, with a high likelihood, the minimum likelihood depending on the desired quality of service and for example equal to 0.99, the correct reception of at least one copy of said information.
The described technology in particular applies to a transmission network working by frequency hopping in a predetermined frequency plane, the frequency used for the data transmission being kept during a plateau, called a frequency hopping (FH) plateau, and changing from one FH plateau to another according to a frequency change law.
A transmission method of the aforementioned type is standard. The information to be transmitted is conveyed in a frame comprising NbMot data words T1, . . . , TNbMot, and defined as follows:
[T1∥T2∥ . . . ∥TNbMot], where ∥ symbolizes a data concatenation.
The transmission of the frame is repeated several times in order to guarantee, with a high likelihood, the correct reception of at least one copy of the information. The transmission method comprises a synchronization mechanism between frames, to allow the receiving station to identify each transmitted frame correctly.
Due to the repetition, one of the NbMot words of the frame, such as the first word T1, also contains a frame indicator TPS, said indicator TPS evolving over the course of the repetitions and making it possible to number the frames successively transmitted.
A synchronization information then comprises the synchronization mechanism so that the receiving station recognizes the division into frames and the frame indicator TPS. Upon each repetition of the frame, the value, denoted TPS(i), of the frame indicator TPS evolves such that the receiving station globally knows how to position the received packet.
The transmitting station then transmits the data words T1, . . . , TNbMot in different packets as follows:                packet number 1 containing the first word T1 with the frame indicator with value TPS(1),        packet number 2 containing the second word T2, . . . ,        packet number NbMot containing the word TNbMot, the packets numbered 1 to NbMot forming the first frame,        packet number NbMot+1 containing the first word T1 with the frame indicator with value TPS(2),        packet number NbMot+2 containing the second word T2, . . . ,        packet number 2×NbMot containing the word TNbMot, the packets numbered NbMot+1 to 2×NbMot forming the second frame,        packet number 2×NbMot+1 containing the first word T1 with the frame indicator with value TPS(3),        packet number 2×NbMot+2 containing the second word T2, . . . , and so forth up to a maximum number of frames, defined as a function of a likelihood that the receiving station will correctly obtain each of the data words T1, . . . , TNbMot, that likelihood also being called quality of service.        
The word T1 with the frame indicator whose value TPS(i) evolves is repeated via packets having a number adjacent to 1 modulo NbMot. Likewise, the word T2 is sent in packets having a number adjacent to 2 modulo NbMot, and so forth. The word TNbMot is repeated in packets having a number adjacent to 0 modulo NbMot.
Consequently, for the receiving station to obtain a copy of each word T1, . . . , TNbMot, it must be able to correctly decode NbMot packets not necessarily belonging to the same frame, but each having a different number considering it modulo NbMot.
However, with such a transmission method, the maximum number of frames transmitted in order to guarantee the desired quality of service is high, and the transmission network is then particularly slow to transmit information.